Electronic device display vias

ABSTRACT

An electronic device may have layers of glass for forming components such as a display. A display cover glass layer may overlap an array of pixels. A touch sensor may be formed under the display cover glass layer. Conductive structures such as transparent conductive electrodes or other conductive layers of material may be formed on the outer surface of the display cover glass layer. The electrodes on the outer surface of the display cover glass layer may be coupled to metal contacts and other circuitry on the inner surface of the display cover glass layer using conductive vias. Vias may be provided with barrier layers, opaque coatings, tapers, and other structures and may be formed using techniques that enhance compatibility with chemical strengthening processes.

This application claims the benefit of provisional patent applicationNo. 62/210,275, filed Aug. 26, 2015, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

This relates generally to electronic devices, and, more particularly, toelectronic devices with layers of transparent material such as displaylayers.

Electronic devices such as laptop computers, cellular telephones, andother equipment are often provided with displays. Displays containarrays of pixels that present images to a user. Displays containtransparent layers of material such as glass layers. Some displaysinclude touch sensors.

It may be desirable to interconnect circuitry on one side of a glasslayer in an electronic device to circuitry on another side of a glasslayer, but doing so poses challenges. If care is not taken, signalinterconnect paths between opposing sides of a glass layer will not bereliable, will create undesired visual artifacts, or will consume morespace within an electronic device than desired.

It would therefore be desirable to be able to provide improved ways inwhich to interconnect circuitry on opposing sides of a display layer orother layer in an electronic device.

SUMMARY

An electronic device may have layers of material such as one or morelayers of glass. Glass layers may be used to form layers in a displaysuch as substrate layers and a display cover glass layer.

A display cover glass layer may overlap a liquid crystal display module,an organic light-emitting diode display module, or other displaystructures. A touch sensor may be formed under the display cover glasslayer.

Conductive structures such as transparent conductive electrodes or otherconductive layers of material may be formed on the outer surface of thedisplay cover glass layer. The conductive structures may be used informing touch sensor components or other circuitry. The circuitry on theouter surface of the display cover glass layer may be coupled to metalcontacts and other circuitry on the inner surface of the display coverglass layer using conductive vias.

Vias through the display cover glass layer or other glass display layersmay be provided with barrier layers, opaque coatings, tapers, and otherstructures and may be formed using low temperature processes or othertechniques that enhance compatibility with chemical glass strengtheningprocesses.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an illustrative electronic devicehaving a display in accordance with an embodiment.

FIG. 2 is a perspective view of an illustrative device having with adisplay in accordance with an embodiment.

FIG. 3 is a cross-sectional side view of an illustrative electronicdevice having a display in accordance with an embodiment.

FIG. 4 is a cross-sectional side view of a portion of an electronicdevice having a display layer such as a display cover glass layer with avia in accordance with an embodiment.

FIGS. 5, 6, and 7 are diagrams showing illustrative equipment andoperations involved in forming vias in layers of material such as glassdisplay layers in accordance with an embodiment.

FIG. 8 is a diagram showing illustrative equipment and operationsinvolved in filling vias with conductive material in accordance with anembodiment.

FIG. 9 is a cross-sectional side view of an illustrative via having acoating layer of material to enhance the appearance of the via inaccordance with an embodiment.

FIG. 10 is a cross-sectional side view of an illustrative via having ataper to help reduce contact resistance when coupling the via to a layerof material such as a layer of transparent conductive oxide inaccordance with an embodiment.

FIGS. 11, 12, and 13 are cross-sectional side views of a glass layerwith a via showing how a removable film may be used to help control thefilling of a via with conductive material in accordance with anembodiment.

FIG. 14 is a cross-sectional side view of an illustrative via with abarrier layer to help reduce interactions between chemical strengtheningmaterials in a glass layer and conductive materials such as metal in thevia in accordance with an embodiment.

FIG. 15 is a diagram of illustrative equipment and operations involvedin forming conductive vias in glass layers in accordance with anembodiment.

DETAILED DESCRIPTION

Conductive vias may be used to interconnect circuitry on opposing sidesof a layer of material. The material through which the conductive viasare formed may be polymer such as thermoset polymer, glass, ceramic, orother suitable materials and may be transparent, translucent, or opaque.Arrangements in which the layer of material through which the conductivevias are formed is a clear glass layer for a display may sometimes bedescribed herein as an example.

An illustrative electronic device of the type that may be provided witha display having conductive vias is shown in FIG. 1. Electronic device10 may be a computing device such as a laptop computer, a computermonitor containing an embedded computer, a tablet computer, a cellulartelephone, a media player, or other handheld or portable electronicdevice, a smaller device such as a wrist-watch device, a pendant device,a headphone or earpiece device, a device embedded in eyeglasses or otherequipment worn on a user's head, or other wearable or miniature device,a television, a computer display that does not contain an embeddedcomputer, a gaming device, a navigation device, an embedded system suchas a system in which electronic equipment with a display is mounted in akiosk or automobile, equipment that implements the functionality of twoor more of these devices, or other electronic equipment.

As shown in FIG. 1, electronic device 10 may have control circuitry 16.Control circuitry 16 may include storage and processing circuitry forsupporting the operation of device 10. The storage and processingcircuitry may include storage such as hard disk drive storage,nonvolatile memory (e.g., flash memory or otherelectrically-programmable-read-only memory configured to form a solidstate drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Processing circuitry in control circuitry 16may be used to control the operation of device 10. The processingcircuitry may be based on one or more microprocessors, microcontrollers,digital signal processors, baseband processors, power management units,audio chips, application specific integrated circuits, etc.

Input-output circuitry in device 10 such as input-output devices 18 maybe used to allow data to be supplied to device 10 and to allow data tobe provided from device 10 to external devices. Input-output devices 18may include buttons, joysticks, scrolling wheels, touch pads, key pads,keyboards, microphones, speakers, tone generators, vibrators, cameras,light-emitting diodes and other status indicators, data ports, etc.Input-output devices 18 may include sensors such as an ambient lightsensor, a capacitive proximity sensor, a light-based proximity sensor, amagnetic sensor, an accelerometer, a force sensor, a touch sensor, atemperature sensor, a pressure sensor, a compass, a microphone or othersound sensor, or other sensors. A user can control the operation ofdevice 10 by supplying commands through input-output devices 18 and mayreceive status information and other output from device 10 using theoutput resources of input-output devices 18.

Input-output devices 18 may include one or more displays such as display14. Display 14 may be a touch screen display that includes a touchsensor for gathering touch input from a user or display 14 may beinsensitive to touch. A touch sensor for display 14 may be based on anarray of capacitive touch sensor electrodes, acoustic touch sensorstructures, resistive touch components, force-based touch sensorstructures, a light-based touch sensor, or other suitable touch sensorarrangements. If desired, electrodes, ground plane structures, orstructures for other components may be incorporated into display 14.Transparent electrodes such as capacitive touch sensor electrodes may beformed on the upper and/or lower surfaces of one or more layers indisplay 14. Display 14 may be an organic light-emitting diode display orother light-emitting diode display, a liquid crystal display, a plasmadisplay, an electrowetting display, an electrophoretic display, or othersuitable display.

As shown in FIG. 2, display 14 may be mounted in housing 12. Housing 12,which may sometimes be referred to as an enclosure or case, may beformed of plastic, glass, ceramics, fiber composites, metal (e.g.,stainless steel, aluminum, etc.), other suitable materials, or acombination of any two or more of these materials. Housing 12 may beformed using a unibody configuration in which some or all of housing 12is machined or molded as a single structure or may be formed usingmultiple structures (e.g., an internal frame structure, one or morestructures that form exterior housing surfaces, etc.). Housing 12 mayhave a single body (e.g., when device 10 is a cellular telephone, tabletcomputer, wristwatch device, etc.) or may have multiple body portionsthat are coupled by a hinge (e.g., in a laptop computer). Housing 12 mayalso have other shapes, if desired.

Display 14 may include one or more overlapping arrays of components. Forexample, display 14 may include an array of pixels such as pixels 20.Pixels 20 may be organized in rows and columns and may be used indisplaying images for a user of device 10. Display 14 may also includeone or more array of transparent electrodes such as electrodes 22 and 24(e.g., arrays of capacitive touch sensor electrodes 22 for gatheringtouch input from a user, etc.). Each of these arrays may overlap oversome or all of the area encompassed by display 14.

FIG. 3 is a cross-sectional side view of electronic device 10 of FIG. 2taken along line 32 and viewed in direction 34. As shown in FIG. 3,device 10 may include electrical components 36. Electrical components 36may include integrated circuits, sensors, connectors, batteries, audiocircuits, speakers, microphones, and other input-output devices andcontrol circuitry. Electrical components 36 may be mounted on one ormore substrates such as substrate 30. Substrates such as substrate 30may be formed from plastic, glass, ceramic, other dielectric materials,printed circuits (e.g., rigid printed circuits formed fromfiberglass-filled epoxy or other rigid printed circuit material and/orflexible printed circuits formed from flexible layers of polyimide orsheets of other polymer substrate materials), or other substratematerial.

Display 14 may have an outermost layer such as display cover layer 26.Layer 26 may be formed from a transparent material that helps protectdisplay 14 such as a layer of transparent plastic, clear glass,sapphire, or other protective display layer. Configurations in whichdisplay cover layer 26 is formed from glass are described herein as anexample, so layer 26 may sometimes be referred to as a display coverglass layer or display cover glass.

Display 14 may have a display module such as display module 28. Displaymodule 28 may be a liquid crystal display module or organiclight-emitting diode display module (as examples). Display module 28(sometimes referred to as display structures or display layers) maycontain pixels 20. Pixels 20 may be arranged in a rectangular array ofrows and columns or other suitable layouts to display images for a userof device 10.

Touch sensor structures for display 14 may be embedded within displaymodule 28, may be formed on the underside of display cover glass 26,and/or may be formed on a touch sensor substrate that is interposedbetween display cover glass 26 and display module 28 (as examples). Thetouch sensor structures may be formed from an array of electrodes suchas electrodes 22 of FIG. 2. Electrodes 24 of FIG. 2 (e.g., touch sensorelectrodes) may be formed on display cover glass 26 (e.g., on the outersurface of display cover glass 26). If desired, electrodes 22 and/orelectrodes 24 may be omitted.

Circuit structures in device 10 that overlap pixels 20 such aselectrodes 22 and electrodes 24 may be formed from transparentconductive materials to avoid blocking images that are being displayedby pixels 20. For example, electrodes 22 and electrodes 24 may be formedusing metal layers that are sufficiently thin to be transparent and/ortransparent conductive oxide layers such as layers of indium tin oxideor zinc oxide.

Transparent conductive structures on the outer surface of display coverglass 26 such as conductive structures (electrodes) 24 may beinterconnected with circuitry below display cover glass 26 in theinterior of device 10 using metal-filled vias or other filled ornon-filled conductive vias that pass through display cover glass 26.

A cross-sectional side view of a portion of device 10 showing how viasmay pass through display cover glass 26 is shown in FIG. 4. As shown inFIG. 4, device 10 may include display cover glass 26 mounted to housing12. Conductive structures 24 (e.g., one or more transparent conductingoxide layers that have been patterned to form electrodes, etc.) may beformed on the outer surface of display cover glass 26. One or morelayers of material such as layer(s) 40 may cover structures 24 (e.g.,layers of metal, conductive oxide, transparent polymer layers, inorganicdielectric layers such as clear layers of oxide and other material,antiscratch layers, antireflection layers, and/or other layers ofmaterial).

Metal pads or other conductive contact structures may, if desired, beformed on the opposing inner surface of display cover glass 26 fromstructures 24 (see, e.g., metal contact 44). Conductive vias such asconductive via 42 may pass through display cover glass 26 and mayelectrically couple structures such as structure 24 to structures suchas contact 44. On the front surface of cover glass layer 26, structures24 may overlap and contact the upper surface of via 42 and on the lowersurface of cover glass layer 26, contacts 44 may overlap and contact theopposing lower surface of via 42.

Inside device 10, electrical components such as integrated circuits,signal path structures, or other electrical components may be coupled toconductive vias such as conductive via 42 (and, if desired, may becoupled to other structures such as ink or other opaque maskingmaterial, glass 26, etc.). For example, a flexible printed circuit,integrated circuit, or other electrical component 48 may have signalpaths formed from metal traces. The metal traces may be coupled to via42 through contact 44 using conductive material 46 (e.g., solder,conductive adhesive such as anisotropic conductive film or isotropicconductive adhesive, welds, or other conductive coupling structures).Component 48 may be a flexible printed circuit that contains multipleconductive lines coupled to respective contacts 44 and that routesignals between these contacts and control circuitry 16 and/or mayinclude one or more integrated circuits in control circuitry 16.

If desired, conductive material 46 may be coupled directly between anexposed portion of conductive via 42 and metal traces in component 48without using intervening metal structures such as contacts 44.Moreover, conductive lines, transparent conductive structures other thanstructure 24 of FIG. 4, or other circuitry on the upper surface ofdisplay cover glass 26 may be interconnected to circuitry on the lowersurface of display cover glass 26 using conductive vias 42. The use ofconductive via 42 of FIG. 4 to electrically short conductive structure24 to contact 44 is merely illustrative.

Conductive vias such as via 42 may have any suitable size and shape.With one illustrative configuration, conductive via 42 may have adiameter of about 50 μm, 30-100 μm, more than 10 μm, more than 30 μm,more than 75 μm, less than 400 μm, or less than 150 μm. Conductive via42 may have a height equal to the thickness T of glass layer 26. Thethickness T of layer 26 (and therefore the height of conductive via 42)may be 500 μm, 200-1000 μm, more than 50 μm, more than 250 μm, morethan, 400 μm, less than 700 μm, or other suitable thickness. Structuressuch as structures 24 and/or contacts 44 may be formed from one or moresublayers (e.g., using a single-layer metal deposition process or amulti-layer metallization technique).

To ensure that display cover glass layer 26 is sufficiently robust toresist damage during handling of device 10 by a user, it may bedesirable to chemically strengthen display cover glass layer 26. Anysuitable transparent material may be used in forming a display coverlayer for display 14. With one illustrative configuration, display 14 iscovered with a layer of glass such as aluminosilicate glass. Analuminosilicate glass layer may be strengthened using an ion exchangeprocess in which the glass layer is immersed in a molten potassium saltbath (e.g., a bath maintained at a temperature of about 400° C.). Duringthis chemical treatment, potassium ions from the bath diffuse into theglass and replace sodium ions in the glass, thereby creating compressivestress in the surface of the glass that helps the glass to resistcracking.

In creating conductive via 42, via holes may be formed within glass 26and filled with metals or other conductive materials in a way that iscompatible with the use of glass strengthening techniques such as ionexchange processes. Compatible processes may involve low-temperatureprocesses that are used after ion exchange treatment of glass 26 (so asto prevent damage to the heat treated portions of glass 26) and/orlow-temperature or high-temperature processes that are performed priorto strengthening.

FIG. 5 shows illustrative equipment and operations associated withcreating conductive vias such as conductive via 42 of FIG. 4. As shownin FIG. 5, via formation equipment 50 may be used to create via hole 52in glass layer 26. Via formation equipment 50 may include laser-basedvia formation equipment, equipment that uses both laser light exposureand chemical etching to form vias, photolithographic patterning tools(e.g., deep reactive ion etching or other etching tools for etching viaholes while portions of glass layer 26 are covered with a protectiveetch mask), machining tools (e.g., drills, milling machines, and otherequipment for mechanically forming via holes), water-jet processingequipment, or other drilling tools. If desired, glass layer 26 may bepolished (e.g., using chemical mechanical polishing techniques or otherpolishing techniques to help planarize glass 26 and the structures onglass 26). Planarization may be performed before etching, after etching,before via filling, and/or after via filling, etc.

After forming via hole 52, via filling tool 54 may be used to depositmaterial 58 in via hole 52 of glass layer 26. Material 58 may beconductive as it is deposited (e.g., material 58 may be metal) or may bea material that becomes conductive after heating with heating equipment60. For example, material 58 may be a material such as a liquid polymerthat contains conductive particles such as metal particles or conductivemetal oxide particles such as indium tin oxide particles. When thepolymer cures (at room temperature, upon exposure to ultraviolet light,upon heating with heating equipment 60, etc.), the conductive particlesprovide material 58 with sufficient conductivity to serve as conductivevia 42. As another example, material 58 may be formed from a mixture ofparticles such as a mixture of glass frit (glass particles) and metalparticles that becomes conductive only after sintering at an elevatedtemperature (e.g., 600° C.) with heating equipment 60. To reduce theprocessing temperature of this type of process, the glass frit or othermaterials that are combined with the conductive particles may beconfigured to exhibit a low melting temperature. If desired, othertechniques may also be used in forming conductive material in via hole52 (e.g., metal may be deposited using physical vapor deposition,electroless deposition or other electrochemical deposition, chemicalvapor deposition, etc.).

FIG. 6 is a diagram showing illustrative equipment and operationsinvolved in forming via holes such as via hole 52 in glass layer 26using a laser-based process. As shown in FIG. 6, laser 62 may applylaser light to glass layer 26 to create modified via hole region 64(e.g., a region in which the bulk properties of glass layer 26 have beenchemically and/or physically modified to make the glass more susceptibleto etching). Laser 62 may be a pulsed laser or a continuous wave laserand may operate at infrared wavelengths, ultraviolet wavelengths, orvisible wavelengths.

Modified via hole region 64 is more susceptible to etching (e.g., wetetching) than unmodified portions of glass layer 26, so the material ofregion 64 is preferentially etched when glass layer 26 is exposed toetchant in etching tool 66. The etching process therefore forms via hole52.

Chemical strengthening tool 68 (e.g., a tool that exposes glass layer 26to a molten potassium salt to perform an ion exchange process) may thenbe used to strengthen layer 26 (e.g., prior to filling hole 52 withconductive material as shown in FIG. 5). In this type of arrangement, itmay be desirable to fill via 52 using a relatively low temperatureprocess (e.g., a process below 200° C., below 100° C., or below othersuitable temperatures) to avoid compromising the strength of the treatedglass. An example of a low-temperature conductive material depositionprocess that may be used in filling via hole 52 is a deposition processin which the conductive material for filing via hole 52 is a liquidpolymer with conductive particles (e.g., a conductive ink containing aliquid polymer and particles of transparent conductive oxide, metalparticles, or other conductive particles). Low temperature plasmaenhanced chemical vapor deposition techniques, physical vapor depositiontechniques such sputtering or evaporation, electrochemical depositiontechniques, and/or other conductive material deposition and patterningtechniques may also be used in depositing some or all of the conductivematerial of conductive vias 42.

It may be desirable to control the profile of via hole 52 (e.g., to formvertical sidewalls, tapered sidewalls, flared sidewalls, etc.). Anillustrative arrangement for forming via holes with tapered sidewalls isshown in FIG. 7. As shown in FIG. 7, modified via hole region 64 may beformed by laser 62. Before etching away region 64, mask deposition tool70 may apply a mask such as mask layer 72 to the upper surface of layer26. Mask layer 72 may be, for example, a layer of polymer. Maskdeposition tool 70 may include equipment for depositing layer 72 usingspinning, spraying, dripping, slit coating, or other suitable coatingtechniques. When glass layer 26 is exposed to etchant using tool 66,modified via hole region 64 will be etched away from the lower surfaceof glass layer 26, resulting in a tapered via hole shape for via hole 52(i.e., a shape in which the diameter of hole 52 is the largest on thelower surface of glass layer 26 where glass layer 26 was uncovered bymasking layer 72 and in which the diameter of hole 52 is smallest on theupper surface of glass layer 26 where mask 72 protects glass 26 fromover-etching). Mask removal equipment 74 may remove mask 72 followingetching (or mask 72 may be retained for use during subsequent processingsteps). After removing mask 72, chemical strengthening tool 68 may beused to strengthen glass layer 26.

If desired, electrochemical deposition techniques may be used indepositing conductive material in via hole 52. An illustrativearrangement for forming conductive via 42 using electrochemicaldeposition is shown in FIG. 8. Initially, via formation equipment 50(e.g., laser 62 and etching tool 66 or other via formation tools) mayform via hole 52 in glass layer 26. Seed layer deposition equipment 80(e.g., physical vapor deposition equipment, atomic vapor depositionequipment or other chemical vapor deposition equipment, etc.) may beused to deposit a thin layer of metal (e.g., a metal coating layer) suchas seed layer 82 on the walls of via hole 52. If desired, a polymerlayer containing catalyst material may be deposited as a coating andexposed to laser light to form seed layer 82. Electrochemical depositionequipment 84 (e.g., electrolytic metal plating equipment and/orelectroless plating equipment) may then be used to electroplateadditional metal into via hole 52, thereby forming conductive via 42.Conductive material may completely fill via 42 or may coat the walls ofvia hole 52 sufficiently to create a conductive path through via 42.

If desired, the appearance of display 14 may be enhanced by depositingmaterials in the vias of layer 26 to help hide the vias from view. Asshown in FIG. 9, for example, a layer of material such as coating layer86 may be deposited on the walls of via hole 52 before depositing metalor conductive material into hole 52. Layer 86 may be a colored ink(e.g., white or black ink formed from metal oxide particles, carbonblack particles, or other pigments or dyes in a polymer binder), orother opaque masking material that helps obscure the metal or otherconductive material of conductive via 42 from view by a user (e.g., toblock metal in via 42 from view by a user such as user 88 of FIG. 9 whois viewing via 42 in direction 90). Structures in device 10 that areoverlapped by the border of display 14 such as housing 12 and/or theunderside of layer 26 that is covered with an opaque masking material(e.g., black or white ink) may be characterized by a color. In this typeof scenario, it may be desirable for the material of layer 86 (e.g.,black or white ink) to be color matched to the material of theoverlapped structures. Conductive vias 42 may also be hidden by usingtransparent conductive material in forming vias 42 that renders vias 42transparent or nearly transparent. For example, indium tin oxideparticles or other transparent conductive particles may be used informing some or all of conductive vias 42 (e.g., to reduce the opticalabsorption that might otherwise be associated with using metal particlesto form vias 42).

To reduce contact resistance between via 42 and conductive structure 24,it may be desirable for the diameter of via 42 to be larger on the uppersurface of glass layer 26 than on the lower surface of glass layer 26.As shown in FIG. 10, for example, via 42 may be provided with an averagediameter of D. Near the bottom of via 42, the diameter of via 42 may beless than D (see, e.g., reduced diameter DB). Contact 44 may be formedfrom a relatively high conductivity material such as metal that allows asatisfactory ohmic contact to be formed between contact 44 and theconductive material in via 42 through the small contact area associatedwith reduced diameter DB. Near the top of via 42, the diameter of via 42may be larger than D (see, e.g., enhanced diameter DT). The relativelylarge size of diameter DT enhances the surface area over which the metalin conductive via 42 contacts the conductive oxide or other conductivematerial of structure 24, thereby reducing the contact resistanceassociated with the connection between structure 24 and via 42.

When depositing metal (e.g., when using physical vapor deposition orother deposition techniques to deposit material into thewidened-diameter end of a tapered via hole), it may be desirable totemporarily cover an opposing end of via hole 52 with a materialretention film such as retention film 92 of FIG. 11. Retention film 92may be a flexible polymer layer such as a polymer sheet that istemporarily attached to the surface of glass layer 26. Duringdeposition, metal or other conductive material fills via hole 52 tocreate conductive via 42. Due to the presence of retention film 92 (and,if desired, a carrier wafer or other carrier structure on film 92 thathelps provide support, etc.), the deposited material does not passthrough via hole 52, as shown in FIG. 12. Following formation ofconductive via 42 by depositing material into via hole 52, film 92 (andthe carrier) may be removed, as shown in FIG. 13. Layer 92 may be atemporary bonding layer that is releasable upon exposure to heat,ultraviolet light, etc.

There may be a risk that potassium from the surface of a chemicallystrengthened glass layer may interact with copper or other metals inconductive via 42. For example, there may be a risk that potassium maydiffuse into the copper or other conductive material, may migrating invia 42, and may migrate along the surfaces of one or more layers ofmaterial in via 42. A barrier layer may be formed in via hole 52 to helpprevent this type of interaction. As shown in FIG. 14, chemicallytreated glass layer 26 may have a core of untreated glass material suchas core 261 and an outer surface layer such as layer 26T that includespotassium that was introduced from the molten potassium salt bath duringthe ion exchange process. Barrier layer 96 may be deposited in via hole52 before depositing metal or other conductive material to formconductive via 42. Barrier layer 96 may be formed from a material thatblocks interaction between the potassium or other potentially reactivematerials of layer 26T and the metal or other materials used in formingconductive via 42 and thereby prevents diffusion of potassium into theconductive material of via 42, migration of the potassium in via 42,migration of potassium along coating layer interfaces (e.g., inner orouter surfaces of barrier layer 96 and/or other coatings in via 42),etc. Barrier layer 96 may be formed from a coating layer such as a layerof silicon nitride, silicon oxynitride, magnesium doped siliconoxynitride, silicon boron nitride, or other inorganic or organic coatinglayer on the wall of via hole 52 or other barrier material.

Some metal deposition processes (e.g., certain chemical vapor depositionprocesses and electroplating processes) may involve elevatedtemperatures. For example, in electroplating processes it may bedesirable to anneal electroplated metal that has been deposited. Toavoid disruptions to layer 26T of glass layer 26 that might arise when astrengthened glass layer is exposed to elevated temperatures, it may bedesirable to perform some or all of the metal deposition operations usedin filling via hole 52 before chemical strengthening operations areperformed on layer 26. This type of approach for forming vias 42 isshown in FIG. 15.

As shown in FIG. 15, via formation equipment 50 may be used to form via52 in glass layer 26. Seed layer deposition equipment 80 may be used todeposit a seed layer such as seed layer 82 in via 52. Depositionequipment 80 may include equipment (e.g., atomic layer depositionequipment or other chemical vapor deposition equipment, etc.) thatexposes glass layer 26 to elevated temperatures. Accordingly, it may bedesirable to use equipment 80 before using chemical strengthening tool68.

Following formation of layer 82, chemical strengthening tool 68 maystrengthen glass layer 26 before electrochemical deposition tool 84fills via hole 52 with additional metal to form via 42 (e.g., using alow temperature filling process) or electrochemical deposition tool 84may fill via hole 52 (and anneal the metal in the filled hole) beforechemical strengthening tool 68 is used to strengthen glass layer 26.

After vias 42 have been formed in glass layer 26, structures such asstructures 24, layers 40, and contacts 44 of FIG. 4 may be formed onlayer 26 and layer 26 may be assembled with other components to formdevice 10.

The foregoing is merely illustrative and various modifications can bemade by those skilled in the art without departing from the scope andspirit of the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. Apparatus, comprising: a glass display layer having via holes; a coating layer inside the via holes; a structure that is overlapped by at least part of the glass display, wherein the coating layer is color matched to the structure; and conductive material in the via holes that forms conductive vias through the glass display layer.
 2. The apparatus defined in claim 1 wherein the coating layer comprises an opaque coating layer.
 3. The apparatus defined in claim 2 wherein the opaque coating layer comprises particles with a polymer binder.
 4. The apparatus defined in claim 3 wherein the conductive material comprises metal, wherein the glass display layer comprises chemically strengthened glass and wherein the metal in the via holes comprises electroplated metal.
 5. The apparatus defined in claim 1 wherein the coating layer comprises a dielectric barrier layer.
 6. The apparatus defined in claim 5 wherein the glass display layer comprises chemically strengthened glass.
 7. The apparatus defined in claim 6 wherein the chemically strengthened glass comprises potassium and wherein the coating layer prevents the potassium from diffusing into the conductive material, migrating in the via, and migrating along the opaque coating layer.
 8. Apparatus, comprising: a glass display layer having via holes; a coating layer inside the via holes; conductive material in the via holes that forms conductive vias through the glass display layer; and transparent conductive oxide structures on the glass display layer, wherein each of the transparent conductive oxide structures is coupled to a respective one of the conductive vias.
 9. The apparatus defined in claim 8 wherein the transparent conductive oxide structures are formed on a first surface of the glass display layer, the apparatus further comprising metal structures that are formed on an opposing second surface of the glass display layer and that are electrically coupled to the conductive vias.
 10. The apparatus defined in claim 9 wherein the via holes are tapered.
 11. The apparatus defined in claim 10 wherein the via holes have first diameters on the first surface and have second diameters that are smaller than the first diameters on the second surface and wherein the glass display layer comprises a chemically strengthened display cover glass layer.
 12. Apparatus, comprising: a display cover glass layer having via holes; transparent conductive material in the via holes that forms conductive vias through the display cover glass layer; and at least one conductive structure on the display cover glass layer, wherein the at least one conductive structure is coupled to a respective one of the conductive vias.
 13. The apparatus defined in claim 12 wherein the transparent conductive material comprises transparent conductive oxide.
 14. The apparatus defined in claim 13 wherein the transparent conductive oxide comprises a material selected from the group consisting of indium tin oxide and zinc oxide.
 15. The apparatus defined in claim 12 further comprising a coating layer in the via holes.
 16. The apparatus defined in claim 15 wherein the coating layer comprises a colored ink.
 17. The apparatus defined in claim 12 wherein the at least one conductive structure comprises a plurality of electrodes.
 18. The apparatus defined in claim 17 wherein the plurality of electrodes comprise touch sensor electrodes.
 19. The apparatus defined in claim 12 wherein the at least one conductive structure comprises transparent conductive oxide.
 20. The apparatus defined in claim 12 wherein the display cover glass comprises first and second opposing surfaces, the via holes have a first diameter at the first surface, the via holes have a second diameter at the second surface, and the first diameter is greater than the second diameter. 